The long range goal of this project is an understanding of the functions and evolution of actin and actin-like proteins. In particular, we are interested in the characterization of actin-like proteins in procaryotic organisms. To this end, we are studying, in detail, the elongation factor Tu of Escherchia coli, a protein which we have shown shares several properties with actin. Next year we plan to 1) complete a study of the in vitro polymerization of EF-Tu, 2) determine the structure of EF-Tu filaments and paracrystals, 3) characterize mutants altered in EF-Tu function and 4) begin a characterization for actin-like proteins in other procaryotes.